Wireless Temperature Sensing Having No Electrical Connections and Sensing Method for Use Therewith

ABSTRACT

A wireless temperature sensor includes an electrical conductor and a dielectric material on the conductor. The conductor is electrically unconnected and is shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the conductor resonates to generate harmonic electric and magnetic field responses, each of which has a frequency associated therewith. The material is selected such that it experiences changes in either dielectric or magnetic permeability attributes in the presence of a temperature change. Shifts from the sensor&#39;s baseline frequency response indicate that the material has experienced a temperature change.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119 ofU.S. Provisional Patent Application No. 61/305,309, filed Feb. 17, 2010,the contents of which are incorporated by reference in their entirety.In addition, this application is co-pending with the related patentapplication entitled “WIRELESS TEMPERATURE SENSOR HAVING NO ELECTRICALCONNECTIONS AND SENSING METHOD FOR USE THEREWITH”, filed on the same dayand owned by the same assignee as this patent application.

ORIGIN OF THE INVENTION

This invention was made in part by an employee of the United StatesGovernment and may be manufactured and used by or for the Government ofthe United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to temperature sensors. More specifically, theinvention is a wireless temperature sensor that includes a materialwhose dielectric or magnetic permeability attributes change withtemperature to thereby change a harmonic response of a nearbyelectrically-unconnected geometric pattern that is electricallyconductive.

2. Description of the Related Art

Well-known temperature sensors include thermocouples, thermistors,transistors with integrated circuits, and optics-based sensors. All ofthese sensors require connection with or to electrical circuit systemsthat provide power and/or control data acquisition. None of thesesystems can operate after sustaining damage that breaks an electricalline or connection point.

Current wireless temperature sensors and sensor system are designed tobe integrated systems that include a sensing element, a power source, atransmitter, a receiver, sending and receiving antenna, and acontroller. System life is limited by the power source. Further, thenumber of elements required for current wireless temperature sensingsystems limits applications to those having enough room and generallyprecludes applications that could make use of an embedded temperaturesensor. Still further, the sensing element is part of an electricallyclosed circuit with electrical connections being required to close thecircuit. If a circuit connection or the closed circuit is broken, thesensor system is rendered useless and must be repaired.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide awireless temperature sensor and sensing system.

Another object of the present invention is to provide a wirelesstemperature sensor and method for using same.

Still another object of the present invention is to provide a wirelesstemperature sensor that can continue to function after sustainingdamage.

Yet another object of the present invention is to provide a wirelesstemperature sensor readily adapted to a variety of installationconfigurations to include those requiring the sensor to be embedded in astructure.

Other objects and advantages of the present invention will become moreobvious hereinafter in the specification and drawings.

In accordance with the present invention, a wireless temperature sensorincludes an electrical conductor and a material in proximity to theconductor. The conductor has first and second ends and shapedtherebetween for storage of an electric field and a magnetic field. Thefirst and second ends remain electrically unconnected such that theconductor so-shaped defines an unconnected open-circuit havinginductance and capacitance. In the presence of a time-varying magneticfield, the conductor so-shaped resonates to generate harmonic electricand magnetic field responses, each of which has a frequency associatedtherewith. The material is selected such that it experiences changes ineither dielectric or magnetic permeability attributes in the presence ofa temperature change. Shifts from the sensor's baseline frequencyresponse indicate that the material has been exposed to a change intemperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a wireless temperature sensor inaccordance with an embodiment of the present invention;

FIG. 2 is a schematic view of a wireless temperature sensor inaccordance with another embodiment of the present invention;

FIG. 3 is a schematic view of a magnetic field response recorder used inan embodiment of the present invention;

FIG. 4 is a schematic view of a wireless temperature sensor to include afield response recorder in accordance with another embodiment of thepresent invention;

FIG. 5 is a schematic view of a spiral trace conductor pattern whosetraces are non-uniform in width;

FIG. 6 is a schematic view of a spiral trace conductor pattern havingnon-uniform spacing between the traces thereof;

FIG. 7 is a schematic view of a spiral trace conductor pattern havingnon-uniform trace width and non-uniform trace spacing;

FIG. 8 is a schematic view of a wireless temperature sensor of thepresent invention incorporated with a wireless electrical device;

FIG. 9 illustrates example damage sequences for puncture to a spiraltrace; and

FIG. 10 shows normalized calibration curves for damage scenarios.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and more particularly to FIG. 1, awireless temperature sensor in accordance with an embodiment of thepresent invention is shown and is referenced generally by numeral 100.Sensor 100 is constructed to be sensitive to local environmentaltemperature changes. In the illustrated embodiment, sensor 100 includesan unconnected electrical pattern 10 and a material 20 in proximity topattern 10.

In general, material 20 is selected to be a material whose dielectricproperties or magnetic permeability properties are altered (e.g.,dielectric constant or magnetic permeability, respectively, increases ordecreases) when in the presence of local temperature changes. As will beexplained further below, material 20 must be within the respondingelectric field of pattern 10 if material 20 is a temperature sensitivedielectric material. If material 20 is a material whose magneticpermeability is temperature sensitive, it must be within the respondingmagnetic field of pattern 10. Material 20 can be, but need not be, inphysical contact with pattern 10. Thus, in general, material 20 must bein proximity to pattern 10. As used herein, the term “proximity”includes the situations where material 20 is near pattern 10 or incontact with pattern 10 as indicated by dashed lines 11. In either case,material 20 will overlap or overlay at least a portion of pattern 10.For the purpose of describing sensor 100, it will be assumed thatmaterial 20 is one whose dielectric properties change with temperature,e.g., piezoceramics, glass, etc. However, it is to be understood thatthe present invention can also be implemented using a material 20 whosemagnetic permeability properties change with temperature.

As will be explained further below, it is the temperature-induced changein dielectric (or magnetic permeability) attributes of material 20 thatallows sensor 100 to be sensitive to temperature changes. Material 20 isplaced in proximity to pattern 10, e.g., deposited on pattern 10 whereit can also serve as a substrate/support of pattern 10 such that sensor100 can be mounted where it is needed, encasing pattern 10, or spaced ashort distance away from pattern 10. Material 20 could be in the form ofa thin, flexible coating or sheet on pattern 10, a thicker sheet insupport of or positioned near pattern 10, or even a thin stripoverlaying some region of pattern 10.

Electrical conductor pattern 10 is any electrical conductor (e.g., wire,run, thin-film trace, etc.) that can be shaped to form an open-circuitpattern that can store an electric field and a magnetic field. The term“open-circuit pattern” as used herein means that the conductor has twoends that are electrically unconnected with the resulting conductorpattern being an electrical open circuit having inductance andcapacitance attributes.

Pattern 10 can be a stand-alone electrically-conductive run or wirerequiring no physical support to sustain its shape. Pattern 10 can alsobe made from an electrically-conductive run or thin-film trace that canbe deposited directly onto material 20, or on/in an optional substratematerial 22 (referenced by dashed lines to indicate the optional naturethereof) that is electrically insulating and non-conductive. Theparticular choice of the substrate material will vary depending on howit is to be attached to material 20 or otherwise mounted in its desiredlocation. Although not a requirement of the present invention, thesurface on which pattern 10 is deposited is typically a planar surface.Because no electrical connections are used, there is no point on pattern10 that, if damaged, renders the sensor non-functional. As will beexplained further below, damage to pattern 10 simply shifts the sensor'sfrequency range allowing it to continue measurement while damaged.

Techniques used to couple pattern 10 and material 20 are as simple asplacing them in non-contacting fixed proximity to each other orphysically attaching them together. Pattern 10 can be deposited onto asupporting substrate made of material 20 using any conventionalmetal-conductor deposition process to include thin-film fabricationtechniques. When both pattern 10 and material 20 (as well as anyoptional substrate material 22) comprise relatively thin flexibleelements, sensor 100 forms a flexible device suitable for mounting on avariety of structures located in a region being monitored for atemperature changes. As will be explained further below, pattern 10 canbe constructed to have a uniform or non-uniform width, and/or uniform ornon-uniform spacing between adjacent portions of the pattern'sruns/traces.

The present invention is not limited to the various constructionsdescribed above. Accordingly, FIG. 2 depicts another embodiment wherematerial 20 is placed on one side of a thermally and electricallyinsulating barrier 30 and pattern 10 is placed on the other side ofbarrier 30. This construction can be used when temperature measurementsmust be taken in hazardous, harsh, high temperature, caustic, etc.,environments, or in the presence of combustible material without anyelectrical component of the measurement system being exposed to theharsh condition. The separation of pattern 10 from any hazardous orcombustible material/environment reduces the potential of dangerousevents. Thus, only material 20 needs to be resilient to the harshenvironments.

The basic features of pattern 10 and the principles of operation forsensor 100 will be explained for a spiral-shaped conductor pattern.However, it is to be understood that the present invention could bepracticed using other geometrically-patterned conductors provided thepattern has the attributes described herein. The basic features of aspiral-shaped conductor that can function as pattern 10 are described indetail in U.S. Patent Publication No. 2007/0181683, the contents ofwhich are hereby incorporated by reference in their entirety. Forpurpose of a complete description of the present invention, the relevantportions of this publication will be repeated herein.

As is well known and accepted in the art, a spiral inductor is ideallyconstructed/configured to minimize parasitic capacitance so as not toinfluence other electrical components that will be electrically coupledthereto. This is typically achieved by increasing the spacing betweenadjacent conductive portions or runs of the conductive spiral pattern.However, in the present invention, pattern 10 exploits parasiticcapacitance. The capacitance of pattern 10 is operatively coupled withthe pattern's inductance such that magnetic and electrical energy can bestored and exchanged by the pattern. Since other geometric patterns of aconductor could also provide such a magnetic/electrical energy storageand exchange, it is to be understood that the present invention could berealized using any such geometrically-patterned conductor and is notlimited to a spiral-shaped pattern.

The amount of inductance along any portion of a conductive run ofpattern 10 is directly related to the length thereof and inverselyrelated to the width thereof. The amount of capacitance between portionsof parallel conductive runs of pattern 10 is directly related to thelength by which the runs overlap each other and is inversely related tothe spacing between the adjacent conductive runs. The amount ofresistance along any portion of a conductive run of pattern 10 isdirectly related to the length and inversely related to the width of theportion. Total capacitance, total inductance and total resistance for aspiral pattern are determined simply by adding the effectivecontributions due to individual segments of the pattern. For example,the effective inductance contribution of a trace segment is theresultant change in the total inductance of pattern 10 due to thechanges in the pattern's distributed self-inductance and distributedmutual inductance due to the addition of the segment. The effectivecapacitance contribution of a trace segment is the resulting change inthe capacitance of pattern 10 due to the addition of the trace segmentas a result of the charge in the segment creating electric fields withthe charges in other parts of pattern 10 thus increasing the totaldistributed capacitance. The geometries of the various portions of theconductive runs of the pattern can be used to define the pattern'sresonant frequency.

Pattern 10 with its inductance operatively coupled to its capacitancedefines a magnetic field response sensor. In the presence of atime-varying magnetic field, pattern 10 electrically oscillates at aresonant frequency that is dependent upon the capacitance and inductanceof pattern 10. This oscillation occurs as the energy is harmonicallytransferred between the inductive portion of pattern 10 (as magneticenergy) and the capacitive portion of pattern 10 (as electrical energy).That is, when excited by a time-varying magnetic field, pattern 10resonates a harmonic electric field and a harmonic magnetic field witheach field being defined by a frequency, amplitude, and bandwidth.

The application of a time-varying magnetic field to pattern 10 as wellas the reading of the induced harmonic response at a resonant frequencycan be accomplished by a magnetic field response recorder. The operatingprinciples and construction details of such a recorder are provided inU.S. Pat. Nos. 7,086,593 and 7,159,774, the contents of which are herebyincorporated by reference in their entirety. Briefly, as shown in FIG.3, a magnetic field response recorder 50 includes a processor 52 and abroadband radio frequency (RE) antenna 54 capable of transmitting andreceiving RF energy. Processor 52 includes algorithms embodied insoftware for controlling antenna 54 and for analyzing the RE signalsreceived from the magnetic field response sensor defined by pattern 10.On the transmission side, processor 52 modulates an input signal that isthen supplied to antenna 54 so that antenna 54 produces either abroadband time-varying magnetic field or a single harmonic field. On thereception side, antenna 54 receives harmonic magnetic responses producedby pattern 10. Antenna 54 can be realized by two separate antennas or asingle antenna that is switched between transmission and reception.

In operation, when pattern 10 is exposed to a time-varying magneticfield (e.g., as generated by recorder 50), pattern 10 resonates harmonicelectric and magnetic fields. The generated magnetic field is generallyspatially larger that the generated electric field. For the illustratedembodiment where material 20 is one whose dielectric properties changewith temperature, material 20 is positioned relative to pattern 10 suchthat it will lie within the generated electric field. However, ifmaterial 20 is one whose magnetic permeability properties change withtemperature (e.g., manganese copper, nickel zinc, manganese zinc, etc.),material 20 is positioned relative to pattern 10 such that it will liewithin the generated magnetic field. By way of example, the operation ofsensor 100 will be described relative to the generated magnetic fieldemanating from pattern 10 when it is exposed to a time-varying magneticfield.

For fixed excitation conditions, the magnetic field response frequencyof pattern 10 is dependent upon the dielectric attributes of anydielectric material placed within the electric field resonated bypattern 10. That is, when a material having dielectric properties (e.g.,material 20) is placed inside the generated electric field of pattern10, the frequency response associated with the generated magnetic andelectric fields around pattern 10 are affected. More specifically, inthe time-varying electric field, dielectric material 20 is polarizedsuch that each molecule acts as an electric dipole moment. Thepolarization of the dielectric material is a function of the electricfield, the dielectric properties of the material, and ambienttemperature. Briefly, the electric field polarizes the dielectricmaterial and the polarization can be modulated by ambient temperature.Temperature changes cause a change in the equivalent capacitance valueof pattern 10 thereby changing the resonant frequency of pattern 10.Accordingly, if the relative positions of pattern 10 and material 20remain fixed and if the dielectric properties of material 20 are fixed,then the magnetic field frequency response of sensor 100 remainsunchanged for fixed excitation conditions. These fixed conditions andresulting magnetic field frequency response of sensor 100 define abaseline response for sensor 100 that is recorded prior to using sensor100.

In the illustrated example, material 20 is a dielectric material thatwill experience a change in its dielectric attributes in the presence ofa temperature change. Accordingly, the response frequency of sensor 100is recorded in conditions where the temperature is stable for aplurality of temperatures. The recorded correlation of temperature andresponse frequency is calibration data that is stored in responserecorder 50. Then, in an unknown temperature environment, the magneticfield frequency response of sensor 100 can be used to measure thetemperature-of-interest. Once temperature/response frequency correlationof sensor 100 is known and sensor 100 is placed in use,interrogation/monitoring of sensor 100 can be carried out continuously,periodically, on-demand, etc., without departing from the scope of thepresent invention.

As mentioned above, a magnetic field response recorder can be used tosupply the time-varying magnetic field used to excite pattern 10 and toread/record the generated magnetic field provided by pattern 10.However, the present invention is not so limited since the excitationtime-varying magnetic field also causes an electric field to be producedby pattern 10. That is, since material 20 is positioned to lie withinthe electric field response of pattern 10, the electric field responsecould also (or alternatively) be monitored. Accordingly, FIG. 4illustrates another embodiment of the present invention where pattern 10of sensor 100 is excited and monitored by a field response recorder 60.Recorder 60 transmits the excitation magnetic field to pattern 10 andmonitors one or both of the generated magnetic and electric fieldresponses of pattern 10. In accordance with the present invention,recorder 60 monitors the frequency of one or both the magnetic andelectric field responses.

Also as mentioned above, both the width of the pattern's conductiveruns/traces and the spacing between adjacent portions of the conductiveruns/traces can be uniform. However, the present invention is not solimited. For example, FIG. 5 illustrates a spiral pattern 40 in whichthe width of the conductive trace is non-uniform while the spacingbetween adjacent portions of the conductive trace is uniform. FIG. 6illustrates a spiral pattern 42 in which the width of the conductivetrace is uniform, but the spacing between adjacent portions of theconductive trace is non-uniform. Finally, FIG. 7 illustrates a spiralpattern 44 having both a non-uniform width conductive trace andnon-uniform spacing between adjacent portions of the conductive trace.

The wireless temperature sensor of the present invention can beconfigured in other ways than described above without departing from thescope of the present invention. The temperature sensor of the presentinvention could also be incorporated in other wireless devices withoutdeparting from the scope of the present invention. For example, FIG. 8illustrates a wireless electrical device that incorporates the presentinvention by placing material 20 between pattern 10 and one or morefloating electrodes 70. In this embodiment, pattern 10 and floatingelectrode(s) 70 define a wireless electrical device such as thatdescribed in U.S. patent publication number 2010/0109818, the contentsof which are hereby incorporated by reference in their entirety.

As another example, the temperature sensor of the present inventioncould be incorporated in a wireless device, such as that described inU.S. patent publication number 2009/0072814 A1, the contents of whichare hereby incorporated by reference in their entirety, to result in asensor capable of measuring rotation (or displacement speed) andtemperature. Sample measurable response mechanisms and respectiveresponse parameters are summarized in Table 1.

TABLE 1 Sensor function list Response Measured Parameters ResponseMechanism parameter Temperature Temperature sensitive Quasi-staticdielectric responding resonant to electric field or frequency changetemperature sensitive magnetic permeable material responding to magneticfield Damage(Puncture, Conductive pattern Abrupt resonant Split,Deformation) change frequency change Motion(Displacement, Energyreceived by Amplitude change Rotation, Position) sensor changes

As yet another example, the temperature sensor of the present inventioncould be incorporated in a wireless device, such as that described inU.S. patent publication number 2009/0302111, the contents of which arehereby incorporated by reference in their entirety, to result in asensor that can concurrently measure temperature and tampering.

As mentioned above, material 20 could also be one whose magneticpermeability properties change with temperature. The above-describedmethods and principles apply equally to this embodiment. An addedadvantage of this embodiment is that the larger spatial extent of themagnetic field generated by pattern 10 would allow a “magneticpermeability-based” material 20 to be located further from pattern 10than a “dielectric-based” material 20.

Regardless of whether material 20 is dielectric-based or magneticpermeability-based, the temperature sensor of the present invention willbe able to perform its function even if its conducting pattern 10 isbroken or damaged such that the pattern as divided into two or more opencircuit patterns. To insure such continued performance, a uniformdistribution of material 20 should cover the physical area of pattern10. Any damage or deformation of pattern 10 will change the sensor'sgeometric parameters and consequently changes the equivalent inductanceand capacitance. Therefore, the sensor shifts its resonant frequency oneach damage event. In most cases, the sensor will remain a resonantcircuit and respond to a time-varying magnetic field. The sensor willalso maintain its temperature sensing function as long as material 20remains in proximity to damaged pattern 10. Since sensor damage changesthe sensor's parameters immediately, the sensor response to damage is anabrupt increase in its resonant frequency while the sensor response totemperature is a continuous and slow process. Therefore, this suddenshift in frequency allows the sensor to be self-sensing to damage. Anysensor response to a damage event can be taken as a frequency baselineshifting in temperature response. As described in U.S. PatentPublication No. 2009/0109005, the contents of which are herebyincorporated by reference on their entirety, when pattern 10 isbroken/damaged to form multiple patterns, the resulting patterns will beinductively coupled to one another such that a new (damaged) sensor isessentially formed that will operate in a new frequency band. Thus, evenif damaged, the sensor of the present invention simply shifts itsfrequency band while retaining its temperature sensing function.

In order for a damaged temperature sensor to continue to function, thesensor needs to be calibrated to define response curves for a number ofpossible and orderly damage scenarios. Then, when an actual sensordamage occurs, the actual response can be compared to the calibrationcurves and used to interpolate a new calibration curve commensurate withthe actual damage as described in U.S. Patent Publication No.2008/0243418, the contents of which are hereby incorporated by referencein their entirety. An approach to accommodate measurement after thesensor has been damaged is to develop a library of the measureand-frequency response curves under a large variety of different damagescenarios, such as those shown in FIG. 9. The measurand in this case istemperature. For example, the puncture to a single trace on each sensoris progressively moved away from the initial inside location on thefirst sensor to the outer position on the last sensor, as shown in FIG.9 a. A similar sequence of damage is repeated as shown in FIG. 9 b,except the puncture width is that of two traces. The damage scenariosresult in a series of response curves, such as the normalizedcalibration curves illustrated in FIG. 10. Each damaged sensor has itsown unique response curve. A uniform distribution of dielectric materialcovering the physical area of the sensor should be used. The result willbe a functioning sensor whose response can be interpreted but may have ahigher measurement error. In a continuous monitoring process, themeasurand (e.g., temperature) value is known before the moment ofdamage. After the damage moment, sensor response frequency jumps to anew point. By using the new response frequency and temperature(temperature is taken as the same before damage event), one can locatethe point on the frequency-temperature surface of the database and findthe closest two curves. These two curves can be used to create anapproximate calibration curve for the damaged sensor, permitting damagedsensors to be used for further measurement of temperature.

The advantages of the present invention are numerous. The wirelesstemperature sensor requires only a simple unconnected, open-circuitconductor shaped to store electric and magnetic fields, and a materialthat experiences a change in its dielectric or magnetic permeabilityattributes in the presence of a temperature change. The chosen materialcan also serve as a substrate or encasement for “packaging” purposes tothereby form a prefabricated or “in situ” wireless temperature sensor.The wireless temperature sensor requires no electrically connectedcomponents, is simple to produce, and can be excited/powered using knownfield response recorder technology. The shaped conductor can beprotected by the chosen material in a potentially harsh environment. Nopower source or other electrical circuit needs to be connected to thesensor and the sensor will continue to function even if damaged. Thepresent invention is further described in Stanley E. Woodard et al 2010Meas. Sci. Technol. 21 075201, the contents of which are herebyincorporated by reference in their entirety.

Although the invention has been described relative to a specificembodiment thereof, there are numerous variations and modifications thatwill be readily apparent to those skilled in the art in light of theabove teachings. It is therefore to be understood that, within the scopeof the appended claims, the invention may be practiced other than asspecifically described.

1. A wireless temperature sensor, comprising: an electrical conductorhaving first and second ends and shaped between said first and secondends for storage of an electric field and a magnetic field, said firstand second ends remaining electrically unconnected such that saidelectrical conductor so-shaped defines an unconnected open-circuithaving inductance and capacitance wherein, in the presence of atime-varying magnetic field, said electrical conductor so-shapedresonates to generate harmonic electric and magnetic field responses,each of which has a frequency associated therewith; and a material inproximity to said electrical conductor, said material experiencingchanges in one of dielectric properties and magnetic permeabilityproperties in the presence of a temperature change.
 2. A wirelesstemperature sensor as in claim 1, further comprising a magnetic fieldresponse recorder for wirelessly transmitting said time-varying magneticfield to said electrical conductor and for wirelessly detecting saidfrequency associated with said magnetic field response so-generated andresulting from said changes.
 3. A wireless temperature sensor as inclaim 1, further comprising an electric field response recorder forwirelessly transmitting said time-varying magnetic field to saidelectrical conductor and for wirelessly detecting said frequencyassociated with said electric field response so-generated and resultingfrom a current state of said dielectric attributes.
 4. A wirelesstemperature sensor as in claim 1, wherein said electrical conductorcomprises a thin-film trace.
 5. A wireless temperature sensor as inclaim 4, wherein said trace is uniform in width.
 6. A wirelesstemperature sensor as in claim 4, wherein spacing between adjacentportions of said trace is uniform.
 7. A wireless temperature sensor asin claim 4, wherein said trace is non-uniform in width.
 8. A wirelesstemperature sensor as in claim 4, wherein spacing between adjacentportions of said trace is non-uniform.
 9. A wireless temperature sensoras in claim 1, wherein said material comprises a dielectric materialselected from the group consisting of piezoceramics and glass.
 10. Awireless temperature sensor as in claim 1, wherein said materialcomprises a magnetic material selected from the group consisting ofmanganese copper, nickel zinc and manganese zinc.
 11. A wirelesstemperature sensor as in claim 1, wherein said material is spaced apartfrom said electrical conductor.
 12. A wireless temperature sensor as inclaim 1, wherein said electrical conductor and said material areflexible.
 13. A wireless temperature sensor, comprising: anelectrically-insulating substrate; an open-circuit pattern ofelectrically-conductive material on a face of said substrate, saidpattern having two electrically unconnected ends, said pattern shapedfor storage of an electric field and a magnetic field, said patternhaving inductance and capacitance that allows said pattern to generateharmonic electric and magnetic field responses when in the presence of atime-varying magnetic field, each of said electric and magnetic fieldresponses having a frequency associated therewith; and a material inproximity to said electrical conductor, said material experiencingchanges in one of dielectric properties and magnetic permeabilityproperties in the presence of a temperature change.
 14. A wirelesstemperature sensor as in claim 13, further comprising a magnetic fieldresponse recorder for wirelessly transmitting said time-varying magneticfield to said pattern and for wirelessly detecting said frequencyassociated with said magnetic field response so-generated and resultingfrom said changes.
 15. A wireless temperature sensor as in claim 13,further comprising an electric field response recorder for wirelesslytransmitting said time-varying magnetic field to said pattern and forwirelessly detecting said frequency associated with said electric fieldresponse so-generated and resulting from said changes.
 16. A wirelesstemperature sensor as in claim 13, wherein said substrate is flexible.17. A wireless temperature sensor as in claim 13, wherein said firstface is planar and wherein said pattern is a spiral trace.
 18. Awireless temperature sensor as in claim 17, wherein said spiral trace isuniform in width.
 19. Wireless temperature sensor as wherein no betweenadjacent portions of said spiral trace is uniform.
 20. A wirelesstemperature sensor as in claim 17, wherein said spiral trace isnon-uniform in width.
 21. A wireless temperature sensor as in claim 17,wherein spacing between adjacent portions of said spiral trace isnon-uniform.
 22. A wireless temperature sensor as in claim 13, whereinsaid material comprises a dielectric material selected from the groupconsisting of piezoceramics and glass.
 23. A wireless temperature sensoras in claim 13, wherein said material comprises a magnetic materialselected from the group consisting of manganese copper, nickel zinc andmanganese zinc.
 24. A wireless temperature sensor as in claim 13,wherein said material is spaced apart from said electrical conductor.25. A wireless temperature sensor as in claim 13, wherein saidelectrical conductor and said material are flexible.
 26. A wirelesstemperature sensor, comprising: an electrical conductor in the form of athin-film trace having first and second ends and shaped to form apattern that can store an electric field and a magnetic field, saidfirst and second ends remaining electrically unconnected such that saidelectrical conductor so-shaped defines an unconnected open-circuithaving inductance and capacitance wherein, in the presence of atime-varying magnetic field, said electrical conductor so-shapedresonates to generate harmonic electric and magnetic field responses,each of which has a frequency associated therewith; a material inproximity to said electrical conductor, said material experiencingchanges in one of dielectric properties and magnetic permeabilityproperties in the presence of a temperature change; and a field responserecorder for wirelessly transmitting said time-varying magnetic field tosaid electrical conductor and for wirelessly detecting said frequencyassociated with at least one of said electric and magnetic fieldresponses so-generated and resulting from said changes.
 27. A wirelesstemperature sensor as in claim 26, wherein said trace is uniform inwidth.
 28. A wireless temperature sensor as in claim 26, wherein spacingbetween adjacent portions of said trace is uniform.
 29. A wirelesstemperature sensor as in claim 26, wherein said trace is non-uniform inwidth.
 30. A wireless temperature sensor as in claim 26, wherein spacingbetween adjacent portions of said trace is non-uniform.
 31. A wirelesstemperature sensor as in claim 26, wherein said material comprises adielectric material selected from the group consisting of piezoceramicsand glass.
 32. A wireless temperature sensor as in claim 26, whereinsaid material comprises a magnetic material selected from the groupconsisting of manganese copper, nickel zinc and manganese zinc.
 33. Awireless temperature sensor as in claim 26, wherein said material isspaced apart from said electrical conductor.
 34. A wireless temperaturesensor as in claim 26, wherein said electrical conductor and saidmaterial are flexible.
 35. A method of sensing temperature, comprisingthe steps of: providing an electrical conductor having first and secondends and shaped between said first and second ends for storage of anelectric field and a magnetic field, said first and second endsremaining electrically unconnected such that said electrical conductorso-shaped defines an unconnected open-circuit having inductance andcapacitance wherein, in the presence of a time-varying magnetic field,said electrical conductor so-shaped resonates to generate harmonicelectric and magnetic field responses, each of which has a frequencyassociated therewith; overlaying at least a portion of said electricalconductor so-shaped with a material that experiences changes in one ofdielectric properties and magnetic permeability properties in thepresence of a temperature change; recording a baseline frequencyresponse for said at least one of said electric and magnetic fieldresponses so-generated when temperature is not changing; and monitoringsaid at least one of said electric and magnetic field responsesso-generated for changes in frequency with respect to said baselinefrequency response as an indication of a change in temperature.